Please can anyone answer 3 questions about central heating?

[Martell]

Thanks again everyone for your really helpful advice. Removing the TRV head from rad in lounge means it's quiet (no whooshing water noise). I'm still bleeding the rads but I don't think I'm getting out any air from them unless air is mixed with the water as it comes out of the bleed valve (no air on its own, but the water ffffizzzzes out). Incidentally the water smells metallic. The bathroom and hall rads continue to make a rushing water noise as does the vertical pipe in the hall bringing water from upstairs but this noise doesn't bother me (as long as it's not an indication of air in the system!)

I'm still experimenting with the room stat. It behaved better last night with the TRV off the rad. The hall is not a good place as it's much warmer than the lounge!

The biggest issue now is a drumming noise which was there when the engineer came two weeks ago but which was somewhat masked by the whooshing rad noises. It starts 8 minutes after the boiler fires up and goes off immediately the boiler goes off. I asked the engineer about it and he thought it was part of the air in the system problem and would be eliminated when I got the air out. It's a random, rapid, drumming sound, difficult to pinpoint but it appears to be in the centre of the house (I can't hear it in kitchen or bathroom) and above my head when I'm in the lounge. I feel it's louder if I increase the temperature dial on boiler and quieter (not much) if I decrease it. I've put my head right up against the boiler and I don't think I could hear it. I thought it might be the pipes under the bedroom floors carrying water to one particular rad in a bedroom so I switched off the rad but the noise continued. If this isn't caused by air still in the system I'll have to ask the engineer to come back as it's not loud, but it's really annoying. I'd be really grateful if anyone could tell me what's likely to be causing this. Again, this only started happening a couple of months ago when the system was drained, leaking valves were repaired, 2 new TRV'S were fitted and the system was refilled. Thanks very much again.

 

[dancinplumba]

To be frank, turning the TRV head to the highest setting would be nearly as good as taking the head off altogether, in most circumstances.

not sure about that if fitted vertical

 

[Chuck]

The initial 'air in the system' diagnosis may have given people tunnel vision. It may have been the problem once but after your fine work bleeding the system I suspect it is time to consider other possibilities. I think it is very possible, even likely, that:

Your 'swooshing' noises are turbulence due to the system pump being on too high a setting.

The 'drumming' noise is most likely the noise of pipes rubbing againsts something, e.g. joists as they expand as they heat up.

There is probably a reason the pump is set high, e.g. the system is not correctly balanced and someone turned the pump up to avoid the hassle of rebalancing the system. Or, it may just be that someone replaced the radiator valves with TRVs and left the original constant-displacement rate pump in the system. If the noise goes away when all the TRVs are fully open then this hypothesis is supported. Replacing the pump with a newer constant-head or 'smart' pump may be what's needed.

It's difficult to decide between these possibilities remotely but an experienced heating engineer should be able to get to the bottom of the problem without too much difficulty. If your current guy is not interested/able to fix the problem ask friends and aquaintences for recommendations and find someone who is.

 

[Martell]

The initial 'air in the system' diagnosis may have given people tunnel vision. It may have been the problem once but after your fine work bleeding the system I suspect it is time to consider other possibilities. I think it is very possible, even likely, that:

Your 'swooshing' noises are turbulence due to the system pump being on too high a setting.

The 'drumming' noise is most likely the noise of pipes rubbing againsts something, e.g. joists as they expand as they heat up.

There is probably a reason the pump is set high, e.g. the system is not correctly balanced and someone turned the pump up to avoid the hassle of rebalancing the system. Or, it may just be that someone replaced the radiator valves with TRVs and left the original constant-displacement rate pump in the system. If the noise goes away when all the TRVs are fully open then this hypothesis is supported. Replacing the pump with a newer constant-head or 'smart' pump may be what's needed.

It's difficult to decide between these possibilities remotely but an experienced heating engineer should be able to get to the bottom of the problem without too much difficulty. If your current guy is not interested/able to fix the problem ask friends and aquaintences for recommendations and find someone who is.

Thank you. It seems then that I can definitely rule out air in the system. I've run the system with all the TRV's fully open and the swooshing noise continues in 2 rads and vertical pipe(s) as it always has from memory. I'm very grateful for your suggestions and there is nothing I feel I could be doing as, of course, I don't have the necessary expertise. It's obvious that I need to call the engineer back. I feel better knowing that I'm not just wasting his time (it's not just air in the system, though I know there was some air til about 10 days ago!). I have 7 years guarantee on the boiler so must go with a Bosch/Worcester trained engineer and I'm happy to go with this guy (he fitted the boiler 3 years ago and services it annually). Having said that, the problems will have to be resolved - especially the drummimg noise - as it's absolutely intolerable. Thanks very much again. I really appreciate your help.

 

[Chuck]

I have 7 years guarantee on the boiler so must go with a Bosch/Worcester trained engineer and I'm happy to go with this guy (he fitted the boiler 3 years ago and services it annually). Having said that, the problems will have to be resolved - especially the drummimg noise - as it's absolutely intolerable. Thanks very much again. I really appreciate your help.

Hmm. If it's a Worcester boiler with a built-in pump they are supplied (AFAIK) with the pump speed set to maximum and instructions to the installer to reduce the setting to the minimum that achieves satisfactory circulation. I've known otherwise quite careful engineers overlook this adjustment and, as a result, leaving the customer with a system that works but has radiators that get hot (unnecessarily) rapidly and lot of hydraulic noise from the pipes.

When correctly set-up, the whole system should have virtually no hydraulic noise, except perhaps when the TRVs are just on the point of closing but you'll only hear that when the house is otherwise quiet.

Good luck.

 

[Martell]

Hmm. If it's a Worcester boiler with a built-in pump they are supplied (AFAIK) with the pump speed set to maximum and instructions to the installer to reduce the setting to the minimum that achieves satisfactory circulation. I've known otherwise quite careful engineers overlook this adjustment and, as a result, leaving the customer with a system that works but has radiators that get hot (unnecessarily) rapidly and lot of hydraulic noise from the pipes.

When correctly set-up, the whole system should have virtually no hydraulic noise, except perhaps when the TRVs are just on the point of closing but you'll only hear that when the house is otherwise quiet.

Good luck.

Thanks again for your support. Difficult to be sure, but I wouldn't have said that my radiators get hot rapidly, especially when winter sets in. In the summer I had major building works done, the building firm noticed some radiator valves were leaking and they repaired them. It was only when I turned on the heating a couple of months ago that I realised I'd been left with problems! So I think that the boiler installation was all correct as were the first couple of services. Anyway, I'll ask him to come back and sort it out. Thanks again.